Spinels like magnetite absorb microwave radiation.

[Charles]

In my further search around the potential use of magnetic wood to protect against Microwave Radiation (see http://www.cassiopaea.org/forum/index.php?topic=322&p=5 ), I have come to some hmmm ... things, pictures, processes and such that I think some might enjoy, play with, or will notice how it initiates associations with bits in their personal knowledge base. This is just a hunch I have, but you never know, so I decided to post it anyway, and thought this to be the appropriate section.

In a patent published in 1977 http://www.freepatentsonline.com/4003840.html I read:

It is generally known to those skilled in the art that ferrites absorb microwave such as those of 500 MHz to 12 GHz to change the microwave energy to a thermal energy. The ferrite is a sintered body having the spinel structure and it is a compound having the following general formula:

MFe.sub.2 O.sub.4

(wherein M is a divalent metal such as Mn, Ni, Cu, Zn, Mg, Co, etc.).

http://en.wikipedia.org/wiki/Spinel

The spinels are any of a class of minerals which crystallize in the isometric system with an octahedral habit. The general formula is as (X)(Y)2(O2-)4, with X representing cations occupying [/b]tetrahedral[/b] sites and Y cations occupying [/b]octahedral[/b] sites. Divalent, trivalent, and quadrivalent cations can occupy the X and Y sites, and they include Mg, Zn, Fe, Mn, Al, Cr, Ti, and Si.

Also Magnetite is such ferrite compound wherein M is Fe (iron) again.

In human brain tissue there is an accumulation of magnetite.

The structure too is intriguing. The core of a spinel structure exists of 21 oxygen atoms, and 24 cations:
8 are surrounded by four atoms and occupy tetrahedral positions,
16 are surrounded by six atoms and occupy octahedral positions.

The red balls represent those that occupy tetrahedral positions while the yellow balls represent those occupying octahedral positions.